Because we needed to single out Black lives, as it was about them being oppressed.
So right now there is no question that the issue at hand is antisemitism. There is no rise in Islamophobia or discrimination against Arabs. Some of these colleges are bending over to appease them and obviously the President is only condemning them using the same sentiment as "all lives matters".
Now, all that being said. If these riots and protests do not get under control in the near future, there very well could be a long term rise in people not appreciating these antisemitic Muslims such as Rep Omar and others in positions of power. Not saying it will come to violence, but there just might be a little animosity growing.
The reality here is that Joe Biden is not taking sides in this matter, and this is not making either side happy, as much as he is attempting to appease everyone. Make no mistake, this liberal rise in antisemitic behavior is going to push Jews away from Biden and Democrats, while the crybaby antisemitic revolutionaries are upset that their concerns are not being taken seriously. Because at the end of the say their terror group (Hamas) is getting wiped out and no rhetoric from the President is going to help the pro-Palestinian voters get over that very real reality.
Bottom line: Biden and the Democrats are losing Muslim and Arab voters because those voters see them as "allowing" Israel to tear down Hamas and destroy Palestine. He loses the Jews, because he refused to condemn the antisemitism without just lumping it in with everything else, while doing absolutely nothing concrete to stop it.